In various commercial and military applications, it may be helpful to keep a sensor pointed at a fixed location in space, even as the platform on which the sensor is mounted moves. For example, a helicopter (e.g., a news helicopter or a firefighting helicopter) may include a video camera on a gimbal which may be used to monitor a fixed location on the ground while the helicopter flies in a circle to avoid the risk and increased fuel cost associated with hovering. In such a situation, a human operator may initially aim the sensor at a target of interest, and, in some systems, one or more inertial sensors may be employed to monitor subsequent motion of the platform, from which gimbal pointing changes may be calculated to cancel the effects of the platform motion, and corresponding commands may be sent to the gimbal to keep the sensor pointed at the target. In some cases, e.g., on a helicopter used for firefighting, tracking of the target may also be used, for example, to delivery fire retardant to the target, which may be a fire or a location (e.g., a building) to be protected from fire.
Systems based on inertial sensors, however, may suffer from drift. Moreover, the algorithms used to calculate the desired gimbal pointing changes may rely on information about the elevation of the target, which may be inaccurate, for example if the target is on a tall building not included in the elevation model used.
Thus, there is a need for an improved system and method for sensor pointing control.